/* ContentReader.java                                              NanoXML/Java
 *
 * $Revision: 1.4 $
 * $Date: 2002/01/04 21:03:28 $
 * $Name: RELEASE_2_2_1 $
 *
 * This file is part of NanoXML 2 for Java.
 * Copyright (C) 2000-2002 Marc De Scheemaecker, All Rights Reserved.
 *
 * This software is provided 'as-is', without any express or implied warranty.
 * In no event will the authors be held liable for any damages arising from the
 * use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 *  1. The origin of this software must not be misrepresented; you must not
 *     claim that you wrote the original software. If you use this software in
 *     a product, an acknowledgment in the product documentation would be
 *     appreciated but is not required.
 *
 *  2. Altered source versions must be plainly marked as such, and must not be
 *     misrepresented as being the original software.
 *
 *  3. This notice may not be removed or altered from any source distribution.
 */

package net.n3.nanoxml;

import java.io.IOException;
import java.io.Reader;

/**
 * This reader reads data from another reader until a new element has been
 * encountered.
 * 
 * @author Marc De Scheemaecker
 * @version $Name: RELEASE_2_2_1 $, $Revision: 1.4 $
 */
class ContentReader extends Reader {

	/**
	 * The encapsulated reader.
	 */
	private IXMLReader reader;

	/**
	 * Buffer.
	 */
	private String buffer;

	/**
	 * Pointer into the buffer.
	 */
	private int bufferIndex;

	/**
	 * The entity resolver.
	 */
	private IXMLEntityResolver resolver;

	/**
	 * Creates the reader.
	 * 
	 * @param reader
	 *            the encapsulated reader
	 * @param resolver
	 *            the entity resolver
	 * @param buffer
	 *            data that has already been read from <code>reader</code>
	 */
	ContentReader(IXMLReader reader, IXMLEntityResolver resolver, String buffer) {
		this.reader = reader;
		this.resolver = resolver;
		this.buffer = buffer;
		this.bufferIndex = 0;
	}

	/**
	 * Cleans up the object when it's destroyed.
	 */
	protected void finalize() throws Throwable {
		this.reader = null;
		this.resolver = null;
		this.buffer = null;
		super.finalize();
	}

	/**
	 * Reads a block of data.
	 * 
	 * @param outputBuffer
	 *            where to put the read data
	 * @param offset
	 *            first position in buffer to put the data
	 * @param size
	 *            maximum number of chars to read
	 * 
	 * @return the number of chars read, or -1 if at EOF
	 * 
	 * @throws java.io.IOException
	 *             if an error occurred reading the data
	 */
	public int read(char[] outputBuffer, int offset, int size) throws IOException {
		try {
			int charsRead = 0;
			int bufferLength = this.buffer.length();

			if ((offset + size) > outputBuffer.length) {
				size = outputBuffer.length - offset;
			}

			while (charsRead < size) {
				String str = "";
				char ch;

				if (this.bufferIndex >= bufferLength) {
					str = XMLUtil.read(this.reader, '&');
					ch = str.charAt(0);
				} else {
					ch = this.buffer.charAt(this.bufferIndex);
					this.bufferIndex++;
					outputBuffer[charsRead] = ch;
					charsRead++;
					continue; // don't interprete chars in the buffer
				}

				if (ch == '<') {
					this.reader.unread(ch);
					break;
				}

				if ((ch == '&') && (str.length() > 1)) {
					if (str.charAt(1) == '#') {
						ch = XMLUtil.processCharLiteral(str);
					} else {
						XMLUtil.processEntity(str, this.reader, this.resolver);
						continue;
					}
				}

				outputBuffer[charsRead] = ch;
				charsRead++;
			}

			if (charsRead == 0) {
				charsRead = -1;
			}

			return charsRead;
		} catch (XMLParseException e) {
			throw new IOException(e.getMessage());
		}
	}

	/**
	 * Skips remaining data and closes the stream.
	 * 
	 * @throws java.io.IOException
	 *             if an error occurred reading the data
	 */
	public void close() throws IOException {
		try {
			int bufferLength = this.buffer.length();

			for (;;) {
				String str = "";
				char ch;

				if (this.bufferIndex >= bufferLength) {
					str = XMLUtil.read(this.reader, '&');
					ch = str.charAt(0);
				} else {
					ch = this.buffer.charAt(this.bufferIndex);
					this.bufferIndex++;
					continue; // don't interprete chars in the buffer
				}

				if (ch == '<') {
					this.reader.unread(ch);
					break;
				}

				if ((ch == '&') && (str.length() > 1)) {
					if (str.charAt(1) != '#') {
						XMLUtil.processEntity(str, this.reader, this.resolver);
					}
				}
			}
		} catch (XMLParseException e) {
			throw new IOException(e.getMessage());
		}
	}

}
